1. Field of the Invention
The invention relates to a sensor and a driving method of a component of the sensor, and more particularly, to a light sensor and a driving method of a photo transistor of the light sensor.
2. Description of Related Art
A common and widespread way of implementing a light sensor is by using a photodiode or a photo transistor. Whereas the photodiode features a rapid response, it cannot provide a good signal ratio. By contrast, though the photo transistor responds slowly, it has impressive responsibility. Specifically speaking, the photo transistor generates a large number of carriers, i.e. electrons or electron holes, in a channel after irradiation. However, excess carriers generated in an active layer of a common photo transistor as a result of irradiation do not disappear immediately after irradiation, but remain for quite a while. Consequently, the next sensing cannot be performed within a short time. Even though the photo transistor has good light responsibility, which is impractical. Therefore, due to lack of a mechanism to rapidly eliminate photoexcited carriers, common photo transistors have a slow response while having impressive light responsibility. Thus, if a mechanism to rapidly eliminate the excess carriers can be introduced to operation of the photo transistor, residual photoexcited carriers can be rapidly removed after irradiation, so as to achieve real-time sensing.